Method for breaking in aluminum cylinders of an internal combustion engine



United States Patent f 3,303,129 METHGD FOR BREAKING EN ALUMINUM CYLIN- DERS {BF AN HNTERNAL CGMBUSTION ENGINE James W. Johnson, Brooznail, Pa, and James W. Savin, Wenonah, N..E., assignors to The Atlantic Refining Company, Philadelphia, Pin, a corporation of Pennsylvarua No Drawing. Filed July 26, 1965, Ser. No. 474,975 8 Claims. (Cl. 252--37.2)

This invention relates to a process for breaking in the cylinders of an internal combustion engine and more particularly to a process for breaking in the piston rings and aluminum cylinder bores of an internal combustion engine with a break-in lubricating oil composition.

Internal combustion engines normally are subjected to a break-in period whereby the engine is operated at reduced speeds and often under reduced loads in order to mate the freshly machined metal surfaces to each other. The break-in of the engine generally is aided by lubricating with special lubricating oil compositions which commonly are referred to as break-in oils.

There is currently a great deal of interest in manufacturing aluminum internal combustion engines. The aluminum engine has many advantages over the cast iron engine. Since aluminum has a higher thermal conductivity than cast iron, the valves and oil in an aluminum engine run cooler than those in cast iron engines. The aluminum engine is lighter in weight, and has lower octane requirements than the cast iron engine. Also, aluminum can be die cast whereas cast iron cannot. Consequently production costs for an aluminum engine are p0- tentially lower.

A significant problem that has been encountered in the development of the aluminum engine is the slow or otherwise unsatisfactory break-in between the aluminum cylinder bores and the piston rings which generally are made of a metal other than aluminum such as cast iron, steel, or these metals chromium plated. When this break-in is not accomplished, the aluminum cylinder bore becomes scratched, scored and/or scuffed under normal operating conditions thereby causing wear of the metal surfaces. This results in loss of power, excessive consumption of the crankcase lubricant, and reduced engine life.

Various methods have been utilized to accomplish the break-in between the piston rings and aluminum cylinder bores. They have all proved unsatisfactory. For example, different types of break-in oil compositions which perform satisfactorily in breaking in cast iron or steel cylinder bores have been found to be unsatisfactory for breaking in aluminum cylinder bores because of the excessively long periods of time required to achieve the break-in, i.e., up to as much as 5,000 miles of driving under break-in conditions. On the other hand, it has been reported that the break-in may be accomplished in a short period of time with conventional oils if the aluminum cylinder bore is chemically treated to increase oil retention on the surface of the bore. However, such a process adds to the manufacturing cost of the engine and is therefore extremely undesirable.

It is therefore an object of this invention to provide an efficient process for breaking in the piston rings and aluminum cylinder bores of an internal combustion engine.

It is another object of this invention to provide an efiicient process for breaking in the piston rings and aluminum cylinder bores of an internal combustion engine in a relatively short period of time with a break-in lubricating oil composition.

Generally speaking and in accordance with the above objects and their attendant advantages, it has been found that the piston rings and aluminum cylinder bores of an internal combustion engine can be broken in in a very 3,333,129 Patented Feb. 7, 1967 short period of time by the use of a break-in lubricating oil composition containing small amounts of sulfurized sperm oil and lead naphthenate. More specifically, this invention relates to a process for breaking in the piston rings and aluminum cylinder bores of an internal combustion engine with a break-in lubricating oil composition which comprises operating the engine under break-in conditions while lubricating the piston rings and aluminum cylinder bores with a break-in lubricating oil composition comprised of a major amount of a mineral lubricating oil and minor amounts of sulfurized sperm oil and lead naphthenate. The preferred break-in lubricating oil composition is comprised of a petroleum lubricating oil, about 1 to about 10 percent by volume of sulfurized sperm oil and about 0.25 to about 5.0 percent by volume of lead naphthenate. It has been found that exceptionally good break-in results have been obtained with a break-in lubricating oil composition comprised of a solvent refined VI petroleum oil, 5 percent by volume of sulfurized sperm oil, and 1.0 percent by volume of lead naphthenate.

The components of the break-in oil composition of this invention are well known to those skilled in the art. The composition may be made simply by dissolving the sulfurized sperm oil and lead naphthenate into the mineral lubricating oil.

The break-in lubricating oil described hereinabove may be utilized to break-in successfully any aluminum or aluminum alloy cylinder bore. It normally is preferred that the cylinder bore be made from a composition harder than pure aluminum. Consequently, hard aluminum alloy compositions comprised of a major amount of aluminum and minor amounts of other metals such as for example silicon, copper, titanium, iron, cobalt, zinc, etc, are used in the manufacture of the here. These aluminum alloys are well known to those skilled in the art and a typical example would be for instance an aluminum-silicon alloy comprised of in Weight percent 76 to 73 percent aluminum, 16 to 18 percent silicon, 3 to 4 percent copper with smaller amounts of titanium, iron, and cobalt also present. It should be understood, therefore, that alumium as used herein includes within its meaning alumium alloys. The aluminum cylinder bores may be sand cast or die cast and their surface should have, of course, a suitable finish consistent with general and good engine design. It also should be understood that this invention has applicability to aluminum or aluminum alloy cylinder liners which have been fitted into an engine block comprised of a metal other than aluminum.

As stated hereinabove if the break-in between the piston rings and the aluminum cylinder bores is not accomplished, the piston rings, which normally are made from a harder metal than aluminum, scratch, scuff and/ or score the cylinder bores during operation of the engine. Exemplary piston rings that are difficult to break-in with the cylinder bores are cast iron, steel, or these metals chromium plated, and stainless steel.

The break-in may be accomplished simply by filling the crankcase of the internal combustion engine with the break-in lubricating oil composition described hereinabove and operating the engine under any suitable break-in con. ditions for a short period of time, for example, 10 minutes to 1 hour.

To further illustrate this invention, there are included in the table below the results of various cold-start tests, described hereinafter in detail, that were used to evaluate the effectiveness of the break-in oil compositions of this invention and other oil compositions. In these tests, an automobile equipped with a Renault 4-CV engine which was provided with replaceable wet aluminum cylinder liners was utilized. The piston skirts were comprised of epoxy coated aluminum and various types of piston rings 3 were used. Prior to each of the cold-start tests, the engine crankcase was filled with the particular oil composition being tested and the piston rings and aluminum cylinder liners were subjected to a 12 minute break-in. Dur- 4 changed, the crankcase oil was changed, the new liners were broken in and then subjected to the cold-start tests as described above. The results of exemplary tests are shown in the table below.

TABLE I Materials of Construction Break-in Rating of Piston Ring Location as Referred to by y]. No. Cylinder Lmer Example Oil Com- Cold Start Cylinder Number Number position Test Compression Ring Oil Ring 0-1 0-1 C-1 O-1 O-2 O-3 O-4 S-1 8-1 S-1 8- S S E E C-2 0-2 0-2 O-4 O-4 O-4 0-4 8-2 8-3 S-3 S-3 E E E E 0-1 0-1 0-1 O-3 O-3 0-3 O-3 8-1 8-3 8-1 S-3 E E E E 0-1 C-1 C-1 O-4 O-2 O-3 O-4 S-l S-l 8-1 8-1 U U U U 0-1 0-1 0-1 0-5 O-2 O-3 O-4 S-l 8-1 S-1 8- U U U U O-SAE 20 Solvent Refined Base Oil containing 5 vol.. percent sulfurized sperm oil and 1.0 vol. percent lead naphthenate.

OHeavy duty lubricating oil containing about 0.5 wt. percent zinc thioohosphate and 1.0 Wt. percent barium petroleum sulionate.

OSAE Solvent Refined Base Oil containing 1 wt. percent tree sulfur and 1.0 vol. percent lead naphthenate.

0-1Perfect Circle chrome-plated 200 cm. compression ring.

0-2Renau1t chrome-plated compression ring.

C3-Pericct Circle steel compression ring.

ing the break-in, the water jacket and oil sump temperatures were controlled so as not to exceed 180 F. The break-in procedure was as follows:

Step No. Time per Total Time R.p.1n. Load Step, mins.

1 2 2 1, 200 No load 2 2 4 1, 500 Do. 3 2 6 2, 000 Do. 4 2 8 2, 500 Do. 5 2 10 3, 000 D0. 6 1 11 3, 400 Do. 7 1 12 1, 200 Do.

2500 r.p.m. and 16 inch-es of mercury manifold vacuum.

The engine was then shut olf, cooled as described above and subjected to another cold start run on the dynamometer under the same conditions as stated above. This procedure was repeated until a total of 16 cold starts had been made after which the cylinder liners were examined and rated.

In another cold-start test hereinafter referred to as Test B, the engine water jacket was cooled to 30 F. and maintained at this temperature 1-5 F. as the engine was run on the dynamometer at 2000 r.p.m. at 16 inches of mercury manifold vacuum for 2% hours after which the cylinder liners were examined and rated.

After the cold start tests, the cylinder liners were inspected to determine whether they had been broken in properly and were rated accordingly. The break-in of the cylinder liner was given an Excellent rating (E) when visual inspection indicated that the cylinder liner was free of piston ring scratching, scoring, scufiing or any noticeable metal removal. The break-in of the cylinder liner was rated Satisfactory (S) when visual inspection showed localized piston ring polishing, very light scratching or very light localized metal removal. The break-in was considered Unacceptable (U) when visual inspection showed that the cylinder liner was scratched, scored or scuffed to a greater degree than that set forth for a satisfactory rating.

After the cylinder liners were rated, the engine was fitted with new replaceable liners, the piston rings were O1Perfect Circle chrome-plated light expander oil ring. O-2-Perfect Circle chrome-plated heavy expander oil ring. O-3Pedrick chrome-plated oil ring.

O-5Perfect Circle steel heavy expander oil rrng.

S-1Honed aluminum-silicon alloy cylinder liner.

S-Z-Cast iron cylinder liner. S-3Honed and shot pcened aluminum-silicon alloy cyhnder liner.

Examples 1, 2 and 3 in the above table are exemplary of the outstanding break-in results obtained between various types of piston rings and aluminum alloy cylinder bores, when an oil composition of this invention is utilized as the break-in oil. Examples 4 and 5 are illustrative and exemplary of the completely unsatisfactory break-in results obtained with other oil compositions. Example 5 is particularly significant because it shows that an oil composition very similar to the compositions of this invention is not at all eifective in accomplishing the break-in.

By virtue of this invention, there is thus provided a very quick and economical process for breaking in piston rings and aluminum cylinder bores of internal combustion engines.

We claim:

1. A process for breaking in the piston rings and aluminum cylinder b-ores of an internal combustion engine with a break-in lubricating oil composition which comprises operating the engine und-er break-in conditions as the piston rings and cylinder bores are lubricated with a break-in lubricating oil composition comprised of a major amount of a mineral lubricating oil and minor amounts of sulfurized sperm oil and lead naphthenate.

2. The process according to claim 1 wherein said break-in lubricating oil composition is comprised of a petroleum lubricating oil, about 1 to about 10 percent by volume of sulfurized sperm oil and about 0.25 to 5 .0 percent by volume of lead naphthenate.

3. The process according to claim 1 wherein said break-in lubricating oil composition is comprised of a solvent refined VI petroleum oil, 5 percent by volume of sulfurized sperm oil, and 1 percent by volume of lead naphthenate.

4. A process for breaking in the piston rings and aluminum-silicon alloy cylinder bores of an internal combustion engine with a break-in lubricating oil composition which comprises operating the engine under break-in conditions as the piston rings and cylinder bores are lubricated with a break-in lubricating oil composition comprised of a major amount of a mineral lubricating oil and minor amounts of sulfurized sperm oil and lead naphthenate.

5. The process according to claim 4 wherein said break-in lubricating oil composition is comprised of a petroleum lubricating oil, about 1 to about 10 percent by volume of sulfurized sperm oil and about 0.25 to 5.0 percent by volume of lead naphthenate.

6. A process for breaking in the piston rings and aluminum-silicon al-loy cylinder bores of an internal comb-us- 5 6 tion engine with a break-in lubricating oil composition References Cited by the Examiner which comprises operating the engine under break-in UNITED STATES PATENTS g P g 1???? 19 cyillmder glff' 2,136,391 11/1938 Miller 25247.2 103 e W1 3 rea nca mg 0 p 511 11 c 5 3 250 711 5 9 Early 25'2 37 2 prised of a solvent refined 100 VI petroleum oil, 5 percent by volume of sulfurized sperm oil, and 1 percent by FOREIGN PATENTS volume of lead naphthenate. 519,538 12/1955 Canada.

7. The process according to claim 6 wherein said 544,534 8/1957 Canada. piston rings are steel.

8. The process according to claim 6 wherein said pism DANIEL WYMAN Pmary Exammer' ton rings are chrome plated. C. F. DEES, Assistant Examiner. 

1. A PROCESS FOR BREAKING IN THE PISTON RINGS AND ALUMINUM CYLINDER BORES OF AN INTERNAL COMBUSTION ENGINE WITH A BREAK-IN LUBRICATING OIL COMPOSITION WHICH COMPRISES OPERATING THE ENGINE UNDER BREAD-IN CONDITIONS AS THE PISTON RINGS AND CYLINDER BORES ARE LUBRICATED WITH A BREAK-IN LUBRICATING OIL COMPOSITION COMPRISED OF A MAJOR AMOUNT OF A MINERAL LUBRICATING OIL AND MINOR AMOUNTS OF SULFURIZED SPERM OIL AND LEAD NAPHTHENATE. 